Homogeneous Mixing Research Articles

The SARS-CoV-2 Spike Protein Receptor-Binding Domain Expressed in Rice Callus Features a Homogeneous Mix of Complex-Type Glycans.

The spike protein receptor-binding domain (RBD) of SARS-CoV-2 is required for the infection of human cells. It is the main target that elicits neutralizing antibodies and also a major component of diagnostic kits. The large demand for this protein has led to the use of plants as a production platform. However, it is necessary to determine the N-glycan structures of an RBD to investigate its efficacy and functionality as a vaccine candidate or diagnostic reagent. Here, we analyzed the N-glycan profile of the RBD produced in rice callus. Of the two potential N-glycan acceptor sites, we found that one was not utilized and the other contained a mixture of complex-type N-glycans. This differs from the heterogeneous mixture of N-glycans found when an RBD is expressed in other hosts, including Nicotiana benthamiana. By comparing the glycosylation profiles of different hosts, we can select platforms that produce RBDs with the most beneficial N-glycan structures for different applications.

Fabrication of americium containing transmutation targets

An innovative, dust-free method for producing (U,Am)O2-x targets without the generation of Am-contaminated liquid waste has been successfully demonstrated in the Fuel Materials Laboratories at SCK CEN. The method comprises the fabrication of porous uranium oxide microspheres through internal gelation, using starch as a pore-former, and a single-step Am(NO3)3 aqueous solution infiltration process. Various samples containing targeted Am contents of 5, 10, 20, or 30 mol% were prepared. The concentration of the Am(III) stock solution was confirmed by ICP-MS and no other Am species than Am3+ were distinguished by UV–Vis spectrophotometry. The microstructural investigations revealed that the density of the porous host microspheres was approximately 65 %TD, with 30 vol% accessible porosity, suitable for an efficient infiltration. Microstructural analysis using SEM-EDS was performed on the sintered microspheres. Unexpectedly, EDS analysis was found to be incompatible due to detector interference from the 60 keV gamma-rays emitted by the sample. Therefore, examination of cross-sectioned (U,Am)O2-x microspheres was performed using wavelength dispersive spectrometry (WDS), which was unaffected by the soft gamma ray emission. A homogeneous mixing of Am and U was observed, without the formation of agglomerates with distinct doping levels. From the periphery to the center of the microspheres a radial gradient in Am content was observed, indicating a slight enrichment of Am on the surface of the microspheres. Overall, the nominal Am concentration was in very good agreement with the targeted content.

Validation of a CFD model for cell culture bioreactors at large scale and its application in scale-up

Among all the operating parameters that control the cell culture environment inside bioreactors, appropriate mixing and aeration are crucial to ensure sufficient oxygen supply, homogeneous mixing, and CO2 stripping. A model-based manufacturing facility fit approach was applied to define agitation and bottom air flow rates during the process scale-up from laboratory to manufacturing, of which computational fluid dynamics (CFD) was the core modeling tool. The realizable k-ε turbulent dispersed Eulerian gas-liquid flow model was established and validated using experimental values for the volumetric oxygen transfer coefficient (kLa). Model validation defined the process operating parameter ranges for application of the model, identified mixing issues (e.g., impeller flooding, dissolved oxygen gradients, etc.) and the impact of antifoam on kLa. Using the CFD simulation results as inputs to the models for oxygen demand, gas entrance velocity, and CO2 stripping aided in the design of the agitation and bottom air flow rates needed to meet cellular oxygen demand, control CO2 levels, mitigate risks for cell damage due to shear, foaming, as well as fire hazards due to high O2 levels in the bioreactor gas outlet. The recommended operating conditions led to the completion of five manufacturing runs with a 100% success rate. This model-based approach achieved a seamless scale-up and reduced the required number of at-scale development batches, resulting in cost and time savings of a cell culture commercialization process.

Investigation of thermodynamic state evolution, phase transition and mixing of the hydrocarbon droplet in convective supercritical environments

Liquid alkane droplets transit to supercritical fluids under supercritical conditions. However, the subsequent thermodynamic state evolution, phase transition, and mixing in this case, which directly influences combustion in actual diesel engines, need further investigation. We studied the thermodynamic state evolution, phase transition, and mixing of n-heptane droplets in supercritical laminar nitrogen streams through a set of conservation equations. Non-ideal thermodynamic and transport properties were calculated to incorporate the dramatic variation of physical properties in the supercritical regime. We focus on the effects of Reynolds number, ambient pressure, and droplet size on the thermodynamic state evolution, phase transition and mixing of droplets. Results showed that increasing the Reynolds number can accelerate the evolution of thermodynamic states, which leads to the faster transition of droplets from the liquid phase and supercritical fluids to gas-phase mixtures. With the increased Reynolds number, the phase transition rate is increased and the mixing homogeneity is improved due to the enhanced mass transfer. Caused by the negative correlation between mass transfer and ambient pressure, in higher pressure, droplets after the supercritical transition require more time to transition from supercritical fluids to vapor-phase mixtures. Increasing ambient pressure inhibited the droplet phase transition process and deteriorated the mixing homogeneity, but no significant influence was shown on the droplet dynamic evolution process. Smaller droplets transition faster from liquid phase and supercritical fluids to vapor-phase mixtures. The faster thermodynamic state evolution and faster dynamic evolution process of the smaller droplet leads to its more rapid homogeneous mixing with ambient gasses, but the mode of dynamics is independent of the droplet size.

Evaluation of the mixing index in a micromixer of side feeds in a conical chamber

This study delves into the investigation of mixing efficiency in microdevices by augmenting angular momentum within a truncated cone-shaped micromixer through side-feedings. While microchannel flows are typically dominated by molecular transport, characterized by parallel streamlines, this hinders rapid responses in mixing quality. To address this, we evaluate a micromixer featuring side-feedings coupled to a 2D truncated cone, followed by a wavy microchannel. The research assesses the impact of feed arrangement in the entrance section, Reynolds number (Re), and the curvatures of bumps in the wavy microchannel. Symmetrical lateral feeds promote homogeneous mixing in the inlet section where streamlines intersect. At the device outlet, all bump curvatures contribute to a mixing index exceeding 0.90 within a Reynolds number range of 20 to 40. Additionally, lower Reynolds numbers (Re = 0.1) yield a mixing index above 0.90, but with a slower and predominantly diffusive flow. Notably, a sharper curvature geometry results in smaller pressure drops while maintaining a comparable mixing index to other geometries, indicating it as a promising choice for bump curvature.

Creation of Multi-Principal Element Alloy NiCoCr Nanostructures via Nanosecond Laser-Induced Dewetting.

The multi-principal element alloynanoparticles (MPEA NPs), a new class of nanomaterials, present a highly rewarding opportunity to explore new or vastly different functional properties than the traditional mono/bi/multimetallic nanostructures due to their unique characteristics of atomic-level homogeneous mixing of constituent elements in the nanoconfinements. Here, the successful creation of NiCoCr nanoparticles, a well-known MPEA system is reported, using ultrafast nanosecond laser-induced dewetting of alloy thin films. Nanoparticle formation occurs by spontaneously breaking the energetically unstable thin films in a melt state under laser-induced hydrodynamic instability and subsequently accumulating in a droplet shape via surface energy minimization. While NiCoCr alloy shows a stark contrast in physical properties compared to individual metallic constituents, i.e., Ni, Co, and Cr, yet the transient nature of the laser-driven process facilitates a homogeneous distribution of the constituents (Ni, Co, and Cr) in the nanoparticles. Using high-resolution chemical analysis and scanning nanodiffraction, the environmental stability and grain arrangement in the nanoparticles are further investigated. Thermal transport simulations reveal that the ultrashort (≈100ns) melt-state lifetime of NiCoCr during the dewetting event helps retain the constituent elements in a single-phase solid solution with homogenous distribution and opens the pathway to create the unique MPEA nanoparticles with laser-induced dewetting process.

An empirical study of firm characteristics, degree of informality, and productivity heterogeneity in the Indian informal sector

ABSTRACT Traditionally, informal firms are assumed to be a homogeneous mix of firms structurally different from formal firms. However, the emerging literature recognizes the high level of heterogeneity among the informal firms and hypothesizes that these informal firms vary in terms of their degree of informality. The goal of this study is to understand the characteristics of the firms operating at different levels of informality and to investigate its impact on firm performance, using a nationally representative dataset from India. We find that firms that are female-owned, rurally located, unbanked, have small asset sizes, and belong to traditional sectors are more likely to operate at higher informal levels. We also find that less informal firms are more productive. We also estimate the average treatment effect using propensity score matching as a robustness check.

Characterization of multiphase flow through Venturi nozzle using gamma-ray tomography

Venturi-based differential pressure flow meters have proven to be robust and well suited to measure the flowrate of multiphase flow in combination with other measurement techniques. However, important challenges remain in order to reduce the effect of flow regime dependent measurement uncertainties from non-homogeneous flow.Understanding the complexities of multiphase flow through a Venturi is critical, not only for the Venturi flow measurement but also for the potential implications it might have on adjacent measurements affected by the constriction-induced flow perturbations.In this study, we examine the evolution of multiphase flow through a vertically oriented Venturi situated downstream of a T-bend, with a particular emphasis on the effects this might have on associated measurements within a multiphase metering context. Using Gamma-ray tomography, we conducted measurements at the inlet, throat, outlet, and downstream of the Venturi across a wide range of flow rates and Gas Volume Fractions (GVFs). We evaluated gas fraction (GF), slip, and cross-sectional distribution, quantified using measures of asymmetry and annularity.Our findings suggest that deviations between GF and GVF, relative slip velocity, annularity, and asymmetry are generally less at the outlet and downstream of the Venturi compared to the inlet and throat. Notably, annularity exhibits a greater impact than asymmetry on the estimation of bulk fractions from cord measurements.Overall, the study suggests that there may be more favorable conditions for measurements that require a homogeneous mix and less difference between GF and GVF at the outlet or a short distance downstream of the Venturi. However, despite the inlet results showing larger deviations due to inhomogeneous flow compared to the outlet and downstream, these results demonstrate a more predictable pattern in line with predictive models, offering potential benefits for the application of corrective models.

Nanostructured lubricant additives for titanium alloy: Lubrication by the solid-liquid interface with Coulomb repulsion

In this work, the advantage of Coulomb repulsion in the intermolecular forces experienced by molecules on the solid-liquid nanosized contact interface is taken, and the superior friction-reducing property of Cu3(PO4)2·3H2O (CuP) oil-based additives has been confirmed for titanium alloy. Three-dimensional (3D) CuP nanoflowers (CuP-Fs) with a strong capillary absorption effect are prepared to achieve the homogeneous mixing of solid CuP and lubricating oil. Lubrication by CuP-Fs additives for titanium alloy, friction coefficient (COF) can be reduced by 73.68%, and wear rate (WR) reduced by 99.69%. It is demonstrated that the extraordinary friction-reducing property is due to the repulsive solid-liquid interface with low viscous shear force originating from Coulomb repulsion between polar water molecules in CuP and non-polar oil molecules. However, any steric hindrance or connection between this repulsive solid-liquid interface will trigger the adhesion and increase the viscous shear force, for example, dispersant, hydrogen bondings, and shaky adsorbed water molecules. Besides, the lamellar thickness of CuP and the molecular size of lubricant both have a great influence on tribological properties. Here the lubrication mechanism based on interface Coulomb repulsion is proposed that may help broaden the scope of the exploration in low-friction nanomaterial design and new lubricant systems.

Utilizing even Plutonium Isotopes as burnable absorbers for controlling the reactivity and power distribution in Pressurized Water Reactors

In this paper, a new approach is proposed for controlling the reactivity and power distribution in pressurized water reactor cores without the implementation of burnable absorbers. This approach depended on the homogeneous mixing of uranium oxide with even plutonium isotopes; Pu-238, Pu-240, and Pu-242. Three Plutonium fuels; (99% UO2 + 1% Pu-238), (99% UO2 + 1% Pu-240), and (98% UO2 + 0.5% Pu-238 + 1% Pu-240 + 0.5% Pu-242) were simulated using the MCNPX 2.7 code. The three plutonium fuels are compared with the other three erbium fuels; (99.9% UO2 + 0.1% 167Er2O3), (99.74% UO2 + 0.26% 167Er2O3), and (99.61% UO2 + 0.39% 167Er2O3), which are taken as reference fuels. The weight percent of UO2, plutonium isotopes and enriched erbium is adjusted to provide the same initial reactivity. This is important for holding a fair comparison between the two fuel types. The simulation demonstrated that even plutonium isotopes, like enriched erbium, can improve reactor safety parameters. It was found that Pu-240 added fuel can suppress the initial reactivity by 27% and extend the fuel cycle by 6.9% compared to the conventional UO2. The reason for fuel cycle extension is due to the production of Pu-241. Meanwhile, Pu-238 and Pu-even added fuels provide suppressing the initial keff by 13% and 35% and shortening the fuel cycle by 2.7% and 21%, respectively compared to the reference UO2 fuel. Moreover, the fuel temperature coefficient (FTC), moderator temperature coefficient (MTC) and void reactivity coefficient (VRC) of Plutonium fuels are found to more negative than those of erbium fuels at the later stages of burnup because of the spectrum hardening resulting from Pu-239 production.

Impact of flash boiling spray on soot generation of a rich fuel–air mixture under various ambient pressures

Particulate emission is one of the critical challenges for the modern gasoine direct injection (GDI) engines. Especially under cold start conditions, the global equivalence ratio inside the cylinder is often set quite rich, leading to the generation of a large amount of soot. The fuel distribution state, such as homogeneous mixing and heterogeneous mixing with local rich pockets prior to the combustion is the key factor affecting soot generation under cold start conditions in GDI engines. Flash boiling injection, as a method to promote fuel air mixing, could be a potential solution to sooting problems of rich mixture combustion under cold start conditions. However, the unclear influences of flash boiling spray to fuel–air mixing state and subsequent soot generation pose a challenge to soot reduction in GDI engines. This work aims to study the effect of various flash boiling degrees on fuel–air mixture formation and subsequent soot generation utilizing a customized constant volume combustion chamber (CVCC) incorporated with the gasoline direct injection scheme under moderately cold start ambient temperature of 30 °C. A global high equivalence ratio of 1.7 representing extremely rich combustions under cold start conditions is selected for strong sooting propensity. By setting different fuel temperatures (Tf= 30 °C and 120 °C) and various ambient pressures (Pa= 40 kPa, 100 kPa and 160 kPa), various spray flash boiling states (subcooled, transitional flash boiling and flare flash boiling sprays) are achieved, and finally various fuel distribution states of rich mixtures prior to combustion are obtained. High speed color camera and soot sampling TEM grids were used to capture and evaluate the characteristics of spray atomization, combustion and soot aggregate structures. Based on this investigation, the effect of flash boiling degree on fuel–air mixing and subsequent soot generation is analyzed. The results show that flash boiling spray enhances fuel atomization and produces much more homogeneous rich mixture with smaller local rich pockets and richer global premixed gaseous portion. Over-rich global premixed mixture combustion is prone to nuclei inception and agglomeration, producing soot aggregates with small primary particles. While the local rich pocket combustion is prone to surface growth, producing larger primary particles. Flash boiling spray could reduce the size of soot particles under cold start conditions by generating smaller local rich pockets.

Effect of preparation method of pyrolysis liquid mixed with coal on its ignition and combustion characteristics

Relevance. The need to develop technological solutions to increase the competitiveness of pyrolysis processing of various wastes. Combustion of pyrolysis liquid in a mixture with coal is one of these solutions, which makes it possible to stabilize the properties of the obtained fuel and use in standard energy equipment. Aim. To determine the influence of the method of preparing a mixture of pyrolysis liquid and low-grade coal on its ignition and combustion characteristics, as well as on composition of the released gas-phase products, depending on the temperature of heating medium and concentration of the additive. Methods. Pyrolysis and oxidation characteristics were studied using thermogravimetric analysis, and formal kinetic constants were calculated using the Coates–Radfern method. Samples of mixed fuels were prepared by the methods of homogeneous mixing and surface wetting of pyrolysis liquid of rubber processing and low-grade coal. Ignition and combustion characteristics were determined using an experimental stand, and composition of gas-phase combustion products was determined using once-through gas analyzer. Results. The authors have determined the features of pyrolysis and oxidation of the pyrolysis liquid as well as the values of formal kinetics constants, indicating the physical nature of the factors that defining the rate of these processes. It was found that at 600 °C the ignition of the studied mixtures weakly depended on concentration of the additive, while at 700 and 800 °C the dependence was linear, and the differences between the samples prepared using different methods were insignificant. For samples obtained by the method of surface wetting, combustion of the additive occurred in the gas phase near the surface of the sample. For the samples obtained by the method of uniform mixing, it occurred predominantly in the bulk of the backfill. This led to more intense and complete coal combustion in these compositions due to more uniform releasing of heat and initiation of coal particles. The concentration curves of the NO, CO and CO2 release demonstrated, that behavior of the fuel mixture components was additive in terms of released gas-phase combustion products, as well as the absence of significant nonlinear effects over the entire studied range of temperatures and additive concentrations.

Bridging Compartmental Models and Network Analysis in Epidemiological Modelling

In this study, the authors undertake a comparative analysis of compartmental models and network analysis as means of simulating the propagation of infectious diseases. Compartmental models operate under the assumption of homogeneous mixing, which is often a flawed assumption as individuals tend to engage in varied contact patterns based on their surrounding environments. On the other hand, social network analysis accounts for the intricate web of interpersonal connections between individuals, thereby offering a more realistic portrayal of social behaviour. However, network analysis can be computationally demanding, rendering its application in real-time epidemic modelling challenging. By conducting a series of simulations utilising the SIR model and network analysis, the authors accentuate the merits of a hybrid modelling approach that integrates the strengths of both compartmental models and network analysis while mitigating their respective limitations. Additionally, the authors suggest plausible avenues for future research.

Experimental and computational investigation of chaotic advection mixing in laminar rectangular stirred tanks

The phenomenon of chaotic advection mixing in laminar stirred tanks, particularly when handling high-viscosity fluids, represents a common and challenging issue in various chemical and biochemical industrial processes. The effectiveness of these mixing processes is often constrained by the stretching, folding, and squeezing of fluid particles. Previous research efforts have predominantly concentrated on the design and/or optimization of impellers and operation modes to increase the stretching and folding of fluid particles. However, the mechanism of triggering chaos through the squeezing of fluid particles remains comparatively less explored. This study endeavors to address the intricate problem of laminar mixing by proposing the utilization of unbaffled rectangular stirred tanks. Via a combined approach of experimental and computational investigations, we illustrate that the implementation of rectangular stirred tanks yields significant improvements in chaotic mixing within laminar flow regimes. This type of tank not only enhances the convective transport of fluids but also distorts or completely eliminates the segregation regions by squeezing. Remarkably, as the tank L/W ratio increases from 1 to 2.5, the observed asymptotic area coverage from a frontal perspective escalates from approximately 55 % to about 85 %. Concurrently, the dimensionless mixing time decreased significantly from 1950 to 350. Of particular note, macroscopic homogeneous mixing is observed in stirred tanks with L/W ratios of 2 and 2.5 at Re = 29, with dimensionless mixing times of 550 and 350, respectively. This work highlights the potential of rectangular stirred tanks as a simple and cost-effective system for laminar mixing applications. Furthermore, it also hints at the broader applicability of the approach in various industrial mixing contexts, such as the suspension of floating granules, entrainment of air, and others.

Bifunctional phosphorus-doped NiMo oxide/Ni–Fe hydroxide composite for overall water electrolysis: optimized performance with exceptional stability

The achievement of outstanding catalytic activity in water electrolysis is contingent upon the presence of abundant active sites with enhanced kinetics in electrocatalysts. This study focuses on enhancing the catalytic activity of water electrolysis under alkaline conditions by designing P-doped NiMo oxide/Ni–Fe hydroxide composite on Ni foam through a straightforward hydrothermal process. The composite is further annealed with NaH2PO4 and subjected to induced growth via in situ precipitation in an oxalic acid solution containing Fe precursors. The resulting bifunctional catalysts exhibit notable catalytic performance, manifesting overpotentials of 20.5 mV and 69.4 mV for the hydrogen evolution reaction (HER) and 225.9 mV and 271.8 mV for the oxygen evolution reaction (OER) to drive 10 and 100 mA/cm2, respectively. The improved kinetics, attributed to P doping, play a pivotal role in reducing the overpotential of HER. Meanwhile, the homogeneous mixing of Ni and Fe, coupled with the large active surface area, enhances the catalytic performance of OER. The investigation of Mo precursors reveals their significant contribution to structurally shaping the catalysts, thereby influencing excellent OER performance. Collectively, these factors enable overall water electrolysis with low potentials of 1.82 V at 100 mA/cm2, underscoring the efficacy of the developed bifunctional catalysts.

Electrocatalytic Activation in ReSe2-VSe2 Alloy Nanosheets to Boost Water-Splitting Hydrogen Evolution Reaction.

It is challenging to control the electronic structure of 2D transition metal dichalcogenides (TMD) for extended applications in renewable energy devices. Here, ReSe2-VSe2 (Re1- xVxSe2) alloy nanosheets over the whole composition range via a colloidal reaction is synthesized. Increasing x makes the nanosheets more metallic and induces a 1T″-to-1T phase transition at x = 0.5-0.6. Compared to the MoSe2-VSe2 and WSe2-VSe2 alloy nanosheets, ReSe2 and VSe2 are mixed more homogeneously at the atomic scale. The alloy nanosheets at x = 0.1-0.7 exhibit an enhanced electrocatalytic activity toward acidic hydrogen evolution reaction (HER). In situ X-ray absorption fine structure measurements reveal that alloying caused the Re and V atoms to be synergically more active in the HER. Gibbs free energy (ΔGH*) and density of state calculations confirm that alloying and Se vacancies effectively activate the metal sites toward HER. The composition dependence of HER performance is explained by homogenous atomic mixing with the increased Se vacancies. The study provides a strategy for designing new TMD alloy nanosheets with enhanced catalytic activity.

A Sustainable Bio-Filler for Epoxy Composites: Use of Pistachio Shell Powder

The use of natural materials has become a crucial concern for humanity due to the limited quantity of petroleum-based products and their harmful impact on nature. The use of natural materials is inevitable for a greener and more sustainable world. Transforming agricultural industrial waste into a high-value product or a source of fuel can significantly benefit our country's economy and environment. Pistachio shell is one of the agro-industrial wastes and is abundant in our country. Our country can benefit economically and environmentally by utilizing and repurposing discarded shells, whether as fuel or as a valuable commodity. In this study, the shells of pistachios grown in Şanlıurfa were crushed in a stone mortar and reduced to certain sizes and turned into powder. Later, this powder was used as a bio-filler material for epoxy resin. Powders were used at 1% and 2% additive ratios and homogeneous mixing was carried out using both magnetic and ultrasonic mixers. The mechanical properties of the obtained biofilled epoxies were investigated and their microstructures were analyzed. Tensile test, bending test and hardness test were performed as mechanical tests and densities were measured. An improvement of 8% and 15% was detected in the maximum tensile and bending strength, respectively. The hardness and density values also increased by 8% and 1.7%, respectively. As a result of the microstructure analysis, no air bubbles were formed in the samples and no agglomeration occurred. Obtained results revealed that pistachio shell grown in Şanlıurfa can be used as bio-filler material.

A high-efficiency and low-carbon strategy for selective lithium recovery from spent lithium-ion batteries: Combining mechanochemical activation with biomass reduction roasting

Biomass reduction roasting has attracted considerable attention as an emerging strategy for selectively recovering lithium from spent lithium-ion batteries (LIBs). However, the utilization of excessive roasting conditions in current practices results in significant energy consumption and C emissions, thereby hindering further development. Herein, we propose a novel recycling strategy that combines mechanochemical activation (MCA) with biomass reduction roasting. The optimized roasting conditions with MCA pretreatment achieve a 100 °C reduction in roasting temperature, a halving of biomass ratio and roasting time, compared to the case without activation. By analyzing the changes in physicochemical properties of mixed samples (cathode materials and biomass) under different activation conditions and their impacts, the action mechanism of MCA on biomass reduction roasting is revealed. The introduction of MCA pretreatment achieves milder roasting conditions by promoting homogeneous mixing and disrupting NCM crystal structures through the “pre-oxygen elements removal” process. Furthermore, mechanical treatment was applied to enhance the carbonated water leaching process. The results of sustainability analysis and economic evaluation demonstrate that the proposed recycling strategy not only reduces CO2 emissions and energy consumption but also generates considerable benefits. Overall, this high-efficiency and low-carbon recycling strategy provides a promising direction for the development of spent LIBs recycling technology.

Sub-millisecond microfluidic mixers coupled to time-resolved in situ photonics to study ultra-fast reaction kinetics: the case of ultra-small gold nanoparticle synthesis.

We report a continuous microreactor platform achieving sub-millisecond homogeneous reagent mixing (∼300 μs) for a time-resolved study on the synthesis of ultra-small gold nanoparticles (NPs). The microreactor (coupled with small angle X-ray scattering, UV-vis, and X-ray absorption spectroscopy for in situ and in operando characterizations), operates within mixing time frames below system characteristic times, providing a unique opportunity to deepen the comprehension of reaction and phase transition pathways with unprecedented details. The microreactor channel length can be approximated to a given reaction time when operated in continuous mode and steady state. As a result, the system can be statically investigated, eliminating technique-dependent probing time constraints and local inhomogeneities caused by mixing issues. We have studied Au(0) NP formation kinetics from Au(III) precursors complexed with oleylamine in organic media, using triisopropylsilane as a reducing agent. The existence of Au(III)/Au(I) prenucleation clusters and the formation of a transient Au(I) lamellar phase under certain conditions, before the onset of Au(0) formation, have been observed. Taking advantage of the high frequency time-resolved information, we propose and model two different reaction pathways associated with the presence or absence of the Au(I) lamellar phase. In both cases, non-classical pathways leading to the formation of NPs are discussed.

A fractional order impedance model for heterogeneous drug distribution in obese patients during general anesthesia

Personalised pharmacokinetic models imply stepping away from the classical assumption of homogeneous drug mixing in various tissue compartments in the body, with a particular impact on obese patients. In this work, the pharmacokinetic compartmental model structure is revisited to account for non-uniform distribution of uptake/clearance time constants in patients as a nonlinear function of body mass index. Simulations are confirming expected patterns of drug distribution in the body and can account for post-anesthesia side effects up to 72 hours. We apply spectroscopy to extract the complex impedance in fat tissue samples. The data is modelled by a Cole-Cole model, where parameters of the fractional order impedance model are optimized using a genetic algorithm. The findings suggest that fat tissue will exhibit anomalous diffusion when drug uptake and clearance are present.